1. Field of the Invention
This invention relates to fuel powered engines and, more particularly, to the prevention of air pollution in gasoline internal combustion engines such as those generally employed in motor vehicles. Since the problem to which the invention is particularly directed is most acute and best understood in the operation of gasoline-powered motor vehicles, the invention will hereinafter be described in detail by reference thereto.
2. Background of the Prior Art
Great effort has been focused on the problem of air pollution from combustion engines, notably automobiles. Generally speaking, these efforts have been directed towards one of the following two solutions: (1) devices located in the exhaust portion of the automotive engine in order to filter or decompose the exhaust gases; or (2) the use of so-called catalytic converters to upgrade or crack the low octane motive fluids to the point where only light hydrocarbon gases are introduced for generation of power in the engine. As illustrative of the latter approach as well as brief mention of the former, mention may be made of U.S. Pat. No. 3,855,980 issued to Weisz et al.
According to this patent, fuel of a relatively low octane number is passed through a hydrocarbon catalytic converter operated at temperatures above 600.degree. F., the catalytic converter containing a crystalline aluminosilicate catalyst having a specified pore structure and alpha value wherein the relatively low octane number fuel is said to be converted into relatively high octane fuel for operation of the engine.
Over the years research has also been directed towards various systems for improving the efficiency of internal combustion engines by vaporization of the fuel to achieve more complete combustion.
For instance, U.S. Pat. No. 1,138,575 issued to Knaak is directed to a system wherein a heavy oil may be used and thorough vaporization thereof obtained. According to this patent, the oil is heated under pressure up to substantially its cracking point at atmospheric pressure. The pressure is maintained up to the time of its admission into the cylinder. As soon as it is admitted, a large portion consisting of the more volatile matter immediately vaporizes by reason of the pressure being released. In the patented procedure it is said that the volatile constituents of the oil by their expansion assist the vaporization of the heavier constituents, while the entire oil charge is further assisted in vaporization by a charge of hot air admitted adjacent to the oil spray and adapted to mix intimately therewith.
U.S. Pat. No. 2,218,922 issued to Newbury discloses a system for providing a fuel mixture having the proper proportions of gas and air, including a vaporizing chamber connected to the intake manifold and into which a liquid fuel is introduced, an inlet chamber into which exhaust gases are introduced and an outlet chamber into which the exhaust gases are discharged. Vapors produced in the vaporizing chamber are conducted into a mixing chamber where air is introduced to provide the desired mixture.
U.S. Pat. No. 2,982,528 issued to Shelton discloses a carburetor for use in a vapor fuel system including a heater for vaporizing fuel in the carburetor.
U.S. Pat. No. 3,294,381 issued to Schwartz relates to a carburetor in which the fuel is treated by hot exhaust fumes before it is combined with air and fed to the internal combustion engine, in order to increase its efficiency. The fumes-laden fuel is circulated in a manner to free it of inordinately large globules of fuel, thereby insuring that only finely divided and pre-heated fuel of mist-like consistency is directed to the engine intake manifold.
U.S. Pat. No. 3,496,919 issued to Gerrard is directed to the problem that carburetors presently in use deliver much of the fuel and particularly that of the heavier fraction boiling point into the cylinder in an unvaporized condition and during the heat of combustion there is insufficient oxygen present to burn the fuel to release all of the energy stored in the fuel. As a result, a large portion of the energy contained in the fuel is not used and is passed out the exhaust pipe and wasted and the surrounding air is contaminated with these products of combustion. According to the patent, both the lighter and heavier fractions of the fuel are vaporized by first passing them in heat exchange relation to an available heat supply before delivery to the combustion chamber.
U.S. Pat. No. 3,630,698 issued to Baldwin discloses a fuel system for feeding gasoline vapor directly into the intake manifold wherein the liquid gasoline is vaporized into a highly combustible vapor which is then mixed with the necessary amount of air in a venturi section, and this mixture is ultimately fed directly into the manifold. The patented system, which eliminates the carburetor and fuel pump, includes a closed evaporating chamber and delivery tube means communicating between the evaporating chamber and intake manifold for effecting a vacuum in the chamber and for vaporizing the fuel contained therein.
U.S. Pat. No. 3,653,643 issued to Tucker is concerned with providing for the complete combustion of liquid fuel in an internal combustion engine with a corresponding decrease of air pollutant in the exhaust. This is said to be achieved by supplying a completely vaporized or dry gas to the combustion chamber. The primary air for the mixture is initially filtered and then passed through a vaporizing filter immersed in the liquid fuel which breaks the primary air up into small bubbles to increase the surface area available for evaporation of the liquid fuel. Secondary air is then added to the enriched fuel-air mixture prior to admission into the combustion chamber.
U.S. Pat. No. 2,796,855 issued to Schumacher relates to the problem of a small portion of the fuel condensing and accumulating in the form of fine droplets or as a film on the interior surface of the inlet manifold of the engine and thereby adversely affecting the combustibility of the fuel and air mixture. This problem is said to be solved by heating the fuel and maintaining it in a liquid state at a comparatively high temperature and pressure prior to its introduction into the combustion chamber. As the heated liquid fuel flows into the combustion chamber, the pressure upon the liquid is completely released and the liquid fuel immediately vaporizes and issues in the form of a jet.
Finally, U.S. Pat. No. 4,083,340 issued to Furr et al is directed to the concept of heating gasoline under pressure to a temperature higher than its normal boiling point while maintaining it liquid by means of pressure. According to the patent, when the pressure is released, every particle of the gasoline becomes instantly gaseous and mixes thoroughly and evenly with the air rather than forming a mixture of gaseous gasoline, air and droplets of liquid gasoline. Although it is stated in Col. 6 that the patented system was favorably tested on two different automobiles, it is not explained how the patentees solved the problem of vapor lock which applicants find will occur when the fuel heated above its boiling point but maintained in the liquid state is introduced into the conventional carburetor of an automobile.
While the foregoing survey is not intended to be a complete one of the prior art patents, it is believed to be illustrative of the state of the art with respect to the subject matter of the present invention.
Although it can be said that the prior efforts have achieved some success in improving the efficiency of combustion engines and in reducing hydrocarbon and carbon monoxide pollution, it nevertheless remains an acute problem, particularly in areas of dense vehicular population. Recognizing the inability of the prior approaches to provide a satisfactory solution, existing legislation which has been enacted to reduce pollution is in the form of a compromise permitting certain maximum levels of pollutants to be discharged from the exhaust system. However, since the amount of pollution is the sum total of emission of pollutants from all of the vehicles in a given area, it is clear that merely limiting the degree of pollution from a single vehicle is not a satisfactory solution to the problem. Accordingly, a very great need still exists for a better system to control pollution from combustion engines.
The present invention is directed to this great need.